Oscillator crystals are used in oscillator circuits in clockcontrolled, telecommunications equipment because of their stability and reliability. Dependent on the crystal sections, the oscillator crystals have different temperature-dependent resonant frequencies. The temperature dependency is defined by a temperature characteristic or characteristic information individually associated to an oscillator crystal and is calculated or measured during the crystal manufacture. This temperature-related characteristic information and other individual characteristic information of the oscillator crystals, (for example, modification of the oscillator crystal properties due to aging of the oscillator crystal) are communicated to the users of oscillator crystals (particularly for oscillator circuits) on data sheets or are separately communicated in printed form for every crystal. Further, in the prior art legends are used on the oscillator crystals that reference the individual characteristic information of the oscillator crystals on data sheets. The oscillator crystals are preferably utilized in oscillator circuits wherein digital clock signals are formed having a frequency prescribed by the oscillator crystal. Due to the individual properties of the oscillator crystals, the individual characteristic information of the oscillator crystals must be available for high-precision clock controls in the clock devices (particularly in phase-locked loopcontrolled clock devices) that process the digital clock signals and that are connected to the oscillator circuit. Since clock control methods realized by programs are being increasingly provided in the clock means, the input of the individual characteristic information of the oscillator crystals in the oscillator circuit ensues separately for each clock control. This means a substantial added outlay in the allocation of an oscillator circuit to a clock means or to a means wherein a high-precision processing of the clock signals occurs and in which, consequently, the individual characteristic information of the oscillator crystals is to be introduced.